It should be noted that reference to the prior art herein is not to be taken as an acknowledgement that such prior art constitutes common general knowledge in the art.
The term “pump” is used hereinafter to refer to a device that moves fluids (liquids or gases), or sometimes slurries, by mechanical action. The term “submersible pump” is used hereinafter to refer to a device which has a hermetically sealed motor close-coupled to the pump body. The submersible pump includes both the pump and motor being submerged in the fluid to be pumped.
Submersible pumps are usually disposed in deep pits below the level of the liquid to be pumped which, in many cases, is sewage. The pumps are usually lowered into the pumping station along substantially vertical guides fixedly positioned within the pumping station so that the pump outlets may be properly aligned and connected to the outlet pipes of the pumping station without using screws or other manual connecting mechanisms. The pumps are usually lifted from the pumping station by the connection of a hook, wire and winch on a crane truck, directly to the top of the pump. A wire or chain may also be attached to the top of the pump as a backup system, for instance when the well cannot be pumped out and there is no other reasonable way to connect the usual line. These chains typically stretch from the top of the pump and attach to a point close to the top of the pumping station in order to be attached to a lifting device such as a crane. However, it is usually standard practice and required that the well be pumped out before retrieval of the pump begins.
The primary disadvantage of the chain being permanently attached to the pump is that it is more than likely that the wire or chain will be subject to corrosion and or to fouling caused by sludge or solid particles in particular when used for sewerage pumps. Secondly, the use of the extant chain in the lifting process means the crane boom must be significantly higher to cope with the extra chain length. It could also be problematic when used in deep pumping stations where the cost of wires and chains for each and every pump disposed therein can be considerable.
In order to overcome this problem a loop or ring was attached to the top of the pump and with the use of a releasable hook attached to the end of crane cable the pump was lifted out of the pumping station. This method also had a number of disadvantages in particular when used in deep pumping stations. Under current practice, the well is firstly pumped empty. In order to hook the loop or ring onto the pump the driver of the crane, usually assisted by another crew member, then manually guides the hook towards the loop on the exposed pump. The essential difficulty in this task is guiding a free-swivelling hook into a very small, non-standard aperture in, critically, the correct orientation. This method is both troublesome, inherently risky and time consuming.
Moreover, the operator is often subjected to unsafe conditions. Thus, accidents or the threat of accidents occur from time to time which can cause considerable disabilities for the operator. Usually it is a question of fingers or hands getting pinched between the hook and the couple; an operator's finger and hands can be injured or even completely severed. At times injuries to other parts of the body may occur as a result of the fact that the operator stays within the range of movement of the hook where he can be hit by hooks moving in an uncontrolled manner.
Potentially the highest risk of personal injury and or serious and costly damage to the equipment comes from an insecure hook-up of the pump. If the connection fails and the pump drops back into the well, there is an instantaneous emission (splash) of remnant sewage from the bottom of the well which could contact the operators, and severe damage to the pump and associated infrastructure. The sudden release of the load on the lifting wire turns the wire and hook into a lethal projectile.
A typical scenario would be where a sewerage pump is located in a pumping station which is smelly, dirty, often in the dark, and located in a confined space some two to three meters below the ground level or working plane. Under these conditions the workplace involves a number of risks to personnel. As described above the normal practice involves one person operating the crane with a line and hook mechanism, and another person guiding a swivelling hook onto a loop or ring affixed to the top of the submersible pump.
Clearly it would be advantageous if a connecting device could be devised that helped to at least ameliorate some of the shortcomings described above. In particular, it would be beneficial for a lifting device which improves on these deficiencies in particular in improving the safety and labour required to lift and lower a load from a space below the ground or the floor, possibly below a water surface or similar spaces which are difficult to access.